diff --git a/wp-includes/post-thumbnail-template.php b/wp-includes/post-thumbnail-template.php
index 091ffe4811..58315bc60f 100644
--- a/wp-includes/post-thumbnail-template.php
+++ b/wp-includes/post-thumbnail-template.php
@@ -195,7 +195,7 @@ function get_the_post_thumbnail( $post = null, $size = 'post-thumbnail', $attr =
 			$attr = array( 'loading' => $loading );
 		} elseif ( is_array( $attr ) && ! array_key_exists( 'loading', $attr ) ) {
 			$attr['loading'] = $loading;
-		} elseif ( is_string( $attr ) && ! preg_match( '/(^|&)loading=', $attr ) ) {
+		} elseif ( is_string( $attr ) && ! preg_match( '/(^|&)loading=/', $attr ) ) {
 			$attr .= '&loading=' . $loading;
 		}
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 7eb5da1e58..fb36101e2d 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.0-alpha-52573';
+$wp_version = '6.0-alpha-52574';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.